1. Field of the Invention:
This invention relates generally to friction clutches, and more particularly relates to centrifugal clutches in which the frictional elements engage at a predetemined speed of rotation of a power shaft.
2. Prior Art:
Centrifugal friction clutches which engage at a predetermined rotational speed are particularly useful in combination with internal combustion engines which tend to stall under starting load conditions by delaying engagement until the engine is operating at a sufficiently high speed to produce enough torque to prevent stalling. Such centrifugal friction clutches are also particularly useful in connection with small displacement internal combustion engines such as are used in go-carts. One such centrifugal clutch is described in U.S. Pat. No. 4,111,291, and includes a number of plates and discs which move into frictional engagement by pressure exerted by pivoting of weights arranged next to the plates and discs. A demanding application of such a clutch is in racing go-carts, in which any unnecessary size and weight can be a disadvantage. Centrifugal clutches are also known in automatic multispeed transmissions, such as are discussed in U.S. Pat. No. 4,576,269; but such transmissions add a considerable amount of size and weight to a small vehicle, and go-carts or one-quarter midget racing vehicles typically are not equipped with transmissions. It is therefore necessary for the clutch to be continually engaged and disengaged, and it is desirable that the clutch should engage and disengage smoothly, and at approximately at the same speeds. It would be desirable to provide a centrifugal cone clutch with improved mechanical advantage for greater efficiency, compactness and a lighter weight, with a means of adjusting the optimum settings for the speed of engagement and disengagement of the clutch. Furthermore, it would be desirable to provide a centrifugal friction clutch with a reduced friction surface, in order to save in size and weight of the clutch. The present invention meets these needs.